var timer = null;
var offset = 5000;
var index = 0;

//大图交替轮换
function slideImage(i){
  var id = 'image_'+ target[i];
  $('#'+ id)
  .animate({opacity: 1}, 800, function(){
    $(this).find('.word').animate({height: 'show'}, 'slow');
  }).show()
  .siblings(':visible')
  .find('.word').animate({height: 'hide'},'fast',function(){
    $(this).parent().animate({opacity: 0}, 800).hide();
  });
}
//bind thumb a
function hookThumb(){
  $('#thumbs li a')
  .bind('click', function(){
    if (timer) {
      clearTimeout(timer);
    }
    var id = this.id;
    index = getIndex(id.substr(6));
    rechange(index);
    slideImage(index);
    timer = window.setTimeout(auto, offset);
    this.blur();
    return false;
  });
}
//bind next/prev img
function hookBtn(){
  $('#thumbs li img').filter('#play_prev,#play_next')
  .bind('click', function(){
    if (timer){
      clearTimeout(timer);
    }
    var id = this.id;
    if (id == 'play_prev') {
      index--;
      if (index < 0) index = 4;
    }else{
      index++;
      if (index > 4) index = 0;
    }
    rechange(index);
    slideImage(index);
    timer = window.setTimeout(auto, offset);
  });
}
//get index
function getIndex(v){
  for(var i=0; i < target.length; i++){
    if (target[i] == v) return i;
  }
}
function rechange(loop){
  var id = 'thumb_'+ target[loop];
  $('#thumbs li a.current').removeClass('current');
  $('#'+ id).addClass('current');
}
function auto(){
  index++;
  if (index > 4){
    index = 0;
  }
  rechange(index);
  slideImage(index);
  timer = window.setTimeout(auto, offset);
}
$(function(){
  //change opacity
  $('div.word').css({opacity: 0.85});
  auto();
  hookThumb();
  hookBtn();

});